Welcome to the Interaction to Next Paint (INP) Troubleshooting Guide. INP is a Core Web Vital metric that replaced First Input Delay (FID) in March 2024. This guide is designed to help you understand what INP is, how it differs from FID, and why Google made this change. You will also learn how to measure and optimize INP using various tools and techniques. Our goal is to provide you with clear and actionable steps for improving your site's user responsiveness, ensuring a seamless experience for your visitors. Let's dive into how you can optimize your site's performance effectively for INP.

Common symptoms indicating issues with Interaction to Next Paint (INP) include:

1. High Interaction Latency: Users may experience noticeable delays after clicking, tapping, or using keyboard events before the browser responds.
2. Input Delays: A significant wait time before the browser starts processing user interactions.
3. Processing Delays: Prolonged execution time for the site's event handling code, resulting in unresponsive or sluggish behavior.
4. Rendering Delays: Extended time taken by the browser to visually render the next paint after a user interaction.

These symptoms can lead to a decrease in overall user satisfaction and site performance. You can also check your INP score in your Leap dashboard.

Identifying and addressing issues with INP involves several steps and tools. Here are detailed solutions to common problems users may encounter:

1. High INP Scores:
   • Step 1: In Leap go to Measure - My Scores, here you can identify pages with the worst INP scores under the "Worst Pages" section. This will help you pinpoint which pages need immediate attention.
   • Step 2: In the "Worst Pages" section click "view failing interactions" to find out more about that page's score and find interactions that could be improved.
   • Step 3: Use Real User Monitoring (RUM) data available in BDA to analyze the Core Web Vital data collected from real user interactions.
     
   • Step 4: In the Leap Lab section you can use use Total Blocking Time (TBT) as a substitute metric as INP cannot be simulated in the Lab. Optimize TBT as it correlates well with INP.
   • Step 5: Use the Web Vitals Chrome Extension to get live INP readings by interacting with the page manually. Advanced usage includes logging the data to the browser's developer console.
     
   • Step 6: Use Lighthouse, which is accessible in a tab in chrome's developer tools. This has a Timespan Mode that can be used to measure the INP score of a page by manually interacting with it. Full instructions are available on web.dev.
     
     
2. Optimizing JavaScript:
   • Step 1: Enable relevant Leap settings, such as Script Execution, Minify JavaScript, and Content optimizations, that optimize JavaScript loading, parsing, and execution to minimize input and processing delays. Leap's optimization settings contain "tags" that signify which Core Web Vital metrics they are relevant to.
     
   • Step 2: Focus on reducing TBT scores by addressing specific TBT audits in lab tests.
     
     
3. Rendering Delays:
   • Step 1: Optimize the browser’s style recalculations by reducing and simplifying CSS. Leap’s CSS optimization settings can help by removing unused CSS and minifying the CSS that is used.
     
     
4. Identifying Slow Interactions:
   • Step 1: Use Lighthouse's Timespan mode to interact with the page and receive INP-specific audits. These audits can provide insights into which delays are taking the longest and how to address them.
     
   • Step 2: Identify slow interactions using tools like the Web Vitals Chrome Extension and Lighthouse to get detailed information about delays during interactions.
     
     
5. Advanced Optimizations:
   • Step 1: Manually remove unused or mostly unused CSS, JavaScript, and plugins to reduce processing delays.
   • Step 2: Minimize the DOM size of your pages to reduce presentational delays.
   • Step 3: Optimize event handling code if it performs extensive work that delays the browser's next paint. Speed up the code or offload tasks to improve responsiveness.
     
     

By following these steps, you can effectively troubleshoot and optimize your site’s INP scores.

To ensure optimal performance and prevent issues related to Interaction to Next Paint (INP), it is essential to follow these best practices:

1. Optimize JavaScript Loading: Minimize input and processing delays by optimizing how JavaScript is loaded, parsed, and executed. This can help reduce long tasks that delay the browser's ability to process user interactions.
2. Reduce Total Blocking Time (TBT): In lab tests, focus on reducing TBT scores by addressing TBT-specific audits. A lower TBT score can indicate better responsiveness during the initial page load, which correlates with improved INP.
3. Simplify and Optimize CSS: Reduce and simplify CSS to optimize the browser's style recalculations. Removing unused CSS and minifying the CSS that is used can contribute to lower presentational delays and better overall INP scores.

By implementing these tips, you can maintain optimal site performance and ensure a responsive user experience.

If you need further assistance with Interaction to Next Paint, please log in via https://support.ezoic.com/ to make use of our dedicated resources for support. We're here to help!